XA04C 724

6th Meeting of International Group on Research ReactorsApril 29 - May 1, 1998, Taejon, Korea

Utilization and Facility of Neutron Activation Analysis

in HANARO Research Reactor

Y. S. Chung, Y. J. Chung, J. H. MoonKorea Atomic Energy Research Institute

P.O.Box 105 Yusong, 305-600, Taejon, Korea

Abstract

The facilities of neutron activation analysis within a muti-purpose research reactor(HANARO) are described and the main applications of NAA in Korea are reviewed. Thesample irradiation tube, automatic and manual pneumatic transfer system, are installed atthree irradiation holes. One irradiation hole is lined with a cadmium tube for epithen-nalNAA. The performance of the NAA facility was examined to identify the characteristics oftube transfer system, irradiation sites and polyethylene irradiation capsule. The availablethermal neutron flux with each irradiation site are in the range of 39 x 10" - 16 x 10"n/CM2. s and cadmium ratios are 15-250. Neutron activation analysis has been applied in thetrace component analysis of nuclear, geological, biological, environmental and high puritymaterials and various polymers for research and development. Analytical services and thelatest analytical results are summarized.

L Facilities for Neutron Activation Analysis.

1. Irradiation Facilities.There are several types of irradiation facilities such as P, PTS, HTS, OR, IR and beam

tubes in HANARO research reactor. The pneumatic transfer system(PTS) had been mainlyused for neutron activation analysis and a neutron beam will be applied for prompt gammaneutron activation analysis in the near future. Figure I shows the locations of theseirradiation thimbles. PTS is installed at three NAA holes including one Cd lined, and usedfor neutron activation analysis with low heat generation (no more than 75 W) and lighterrabbit (no more than 50g) irradiated in a short time period 130 inutes). Clean dry air andpressure (no more than I bar) is used to transfer the irradiation capsule. The availableneutron flux with each irradiation site and general characteristics of pneumatic transfersystem are presented in Table 1. PTS consists of manual(PTS #1) and automatic(PTS 2)

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types and has been operated since the end of 1996 A 42 cc irradiation capsule is available

for manual PTS. Up to one hundred 27 cc irradiation capsules can be loaded for automatic

PTS at a time. The photograph of PTS laboratory is presented in Figure 2 and the process

flow diagram of automatic PTS is presented in Figure 3 PTS#1 is designed for the

production of short, medium and long-lived isotopes as well as neutron activation analysis. It

is a simple shuttle system which delivers a capsule to the reactor core for a preset

irradiation time under bar of air pressure. At the time-out, the capsule is returned to the

shielded loader/receiver for retrieval by the operator manually and automatically. PTS#2 is

designed only for neutron activation analysis of short and medium-lived isotopes. It is a

somewhat complicated shuttle system which delivers a capsule according to given paths by a

computer control program start from sample loader via automatic sample loader, deverter,

two reactor core, radiation detector, delay stacker, two counters with and without window,

finish to discharged receiver under 06 bar of air pressure. The control program is written in

Microsoft's Visual Basic for Windows which is an extension of Quick Basic that employs

many of the structured features of C and other high level languages. Visual Basic allows

superior implementation of the graphical user interface which is one of the key features of

this capsule transfer program. The graphical user interface allows the operator to easily

determine the exact status of the system at any time by glancing at the computer screen.

The operation of the program starts from main menu of Windows screen disply.

2. Examination of Irradiation.

A new NAA facility is examined to identify the characterization of tube transfer system,

irradiation sites and polyethylene irradiation capsule. The constituent of gamma-ray counting

system for the measurement of radioactivity is presented in Table 2 The temperature of

three irradiation sites were measured with irradiating time using Then-no-Label. In the case

of PTS#1, the internal temperature of PE capsule was no more than 60 IC within hour and

the dose rate was about 3500 rads/sec. in 15MW. The variation of neutron flux in short and

long irradiation intervals were measured in 17MW continuously and were plotted in Figure 4.

Average neutron flux during the period of irradiation was 150±0.02 x 10" n/cm - s. and the

deviation was < .5%. The neutron flux was stable relatively. Thermal, epithenrial and fast

neutron flux of NAA irradiation holes and cadimium ratios were measured in 22MW and

presented in Table 3 To make a suitable polyethylene irradiation capsule, heat resistance

test and physical properties test such as melting index(20.7), density(O.95), melting point(131.

61C), and a measurement of impurities(< 1-100 pm) were carried out and the best materials

were chosen. The analytical results of trace elements in polyethylene rabbit and various

polyethylene materials by INAA and ICP were presented in Table 4.

11. Application of Neutron Activation Analysis in Korea.

Since 1960s, neutron activation analysis (NAA) has been widely used in industry,

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agriculture, geology, environmental pollution, biology, archaeology, forensic science and many

other fields in Korea. There are two NAA groups Korea Atomic Energy Research Institute

(KAERD and Korea Institute of Geology, Mining and Materials (KIGAM) and many users of

universities and other organizations in Korea. In the future, an applied field of NAA will be

extended and users will be increased. The examples of applications of NAA from 1970s are

as follows

*Nuclear Science Trace impurities in nuclear fuel and materials such as uranium oxide,

graphite, reactor coolant and alloy metals were deten-nined using radiochernical NAA

mainly. For the analysis of boron, prompt gamma counting technique was also studied in

1980s. To improve analytical accuracy, spectral and isotope interference occuring from

uranium fission product were studied and interference calibration program was developed

and anticoincidence counting method was studied.

eEnuironrnental Science For a long-term study of the environmental pollution monitoring,

trace and toxic elements in enviromental samples such as air dust, coal and fly-ash, soil,

sediment, plants and sea and river water, rain- and snow fall samples were analyzed.

Recently, XAERI is participating in international cooperative research which is organized

by 1AEA (sub-project on air pollution, UNDP/RCA/IAEA Project). NAA was applied for

the analysis of environmental samples and the migration of trace elements were studied

using tracer method.

*Biological and Medical Science Analysis of a number of animal and plant tissues, ser-um

and blood, fishery, etc. are carried out. Analysis of trace elements in cancer tissues was

performed together with the Korea Cancer Center Hospital.

*Industrial Science Analysis of the composition of high purity materials, noble metals, rare

earth elements and inorganic compounds are carried out. Analytical quality service for QA/

QC in industries are supported. Trace element analysis of igh purity metals and a study

on improvement of accuracy were performed an analytical method of high purity silicon

semiconductor was developed by INAA and analytical methods of high purity Mo, Ni, Ta

and W were also developed by NAA.

Geological Science To improve the analytical sensitivity, a nuclear and a spectral

interferences related to spectrum analysis and irradiation methods were studied. Thecomposition of trace elements in soils, rocks, minerals, etc. were determined using thermal

and epithermal neutron activation analysis. Analysis of rare earth elements in cosmic

materials such as meteorites were carried out as the Apollo project. The isotopes from the

reactions of fast neutron were studied and the interference was also corrected and 40

elements in geological samples were determined.

*Life Science For clinical, nutritional and contamination research, the concentration level of

essential, toxic elements and heavy metal in biological samples such as foodstuff, rice,

human milk, human hair, tabacco and smoke, Korean Ginseng, etc. were analyzed by INAA

and RNAA. Iodine analysis of the colostrurn and mature milk of Korean lactating mothers

related to diseases and metabolism of infants were performed.

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eArchaeology, Forensic Science The origin and classification of Korean antiques was

investigated using chemometrics and multivariate analysis of multi-elements composition in

the pottery and coinages in the laboratory of a university. To study individual identification

for a minal investigation, several kinds of human hair samples were analyzed by INAA,

*Certification of Reference Materials Using NAA technique, cross-checking and

identification of standards has been performed and obtained a good scores in international

and domestic intercomparison and certification of reference materials. Our laboratory is also

carrying out the IAEA's data intercomparison study.

lH. Summary of Applied Research using Neutron Activation Analysis.

1. Study on Air Pollution Monitoring in Korea using High and Low Volume Air

Sampler by Instrumental Neutron Activation Analysis[1-6 : The aim of this research is

to enhance the use of nuclear analytical techniques for air pollution studies and to study the

feasibility of the use of instrumental neutron activation analysis as a routine monitoring tool

to find out environmental pollution sources. Trace elements in samples collected at two

suburban residential sites, Taejon and Wonju city in the Republic of Korea, were analyzed

by INAA. For the verification of the analytical method, NIST SRM-1648 and NIES CRM No.

8 were chosen to be analyzed among the environmental standard reference materials. The

accuracy and precision of the analysis of 43 and 22 trace elements in the samples were

compared with the certified and reported values respectively. The analytical method was

found to be reliable enough when the NEES sample analytical data were compared with the

data from different countries. In the analytical result of SRM, relative standard deviation was

within the 15% except the few elements and the relative error was within the 10%. First, 33

trace elements in airborne particulate matter collected, with the high volume air sampler(PM

10), and silica filters were analyzed. Enrichment factors were calculated using Taylor's

crustal concentration data to investigate the source apportionment. Second, the Gent stacked

filter unit low volume sampler and Nucleopore membrane filters were employed. Variations of

the elemental concentrations were measured monthly and the enrichment factors were

calculated for the fine (PM 25) and coarse size (PM 25-10) fractions, respectively. Total

suspended particulate matter and elemental concentrations in samples collected in the urban

area are measured. The analytical data were treated statistically to estimate the relationship

between two variables, the concentrations of elements and total suspended particulate matter.

The results were used to describe the emission source and their correlation and also

confirmed the possibility to use this method as a routine monitoring tool to find out

environmental pollution sources.

2. Intercomparison and Determination of Trace Elements in Sediments by Instrumental

Neutron Activation Analysis[7 : For the application of study on pollution and conservation

of environment, determination of elemental concentrations in different sediment samples (river,

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estuarine and marine sediment) were carried out using INAA. For verification and evaluation

of the analytical method, three standard reference materials (two NIST SRM and one NRCC

CRM) were chosen and the accuracy and precision of the analytical procedure were estimated

by comparison to the certified values. In addition, two IAEA's sediment samples which were

performed as the IAEA's ACS Programme were analyzed according to the pre-established

analytical method, the analytical results of elements such as Ag, Al, As, Cd, Cr, Cu, Fe, Hg,

Ni, Pb, Sb, Sn and Zn wereintercompared with those of other laboratories.

3. Determination of Toxic and Trace Elements in Algae by Instrumental Neutron

Activation Analysis : Instrurnental neutron activation analysis has been applied in the

determination of toxic and other trace elements in a set of three algae materials provided by

the Intemational Atomic Energy Agency, with the aim of environmental preservation

through enhanced applications of nuclear analytical techniques. The quality of the analysis

method has been evaluated by analyzing a number of biological standard reference materials.

By adding mineral nutrients, the cultivation of algae for metals is enhanced, in particular,

selected toxic heavy metals such as As, Cd, Cr, Hg, Ni and Pb. It is believed that the level

of elemental concentration in algae samples are dependent on environmental conditions due to

its biochemical properties. Algae materials may be useful as an indicator or controller of

environmental water pollution.

4. Determination of Trace Elements in High Purity Copper by INAA, GFAAS and

ICP/AES[8 : Trace elements in high purity copper metal were analyzed by INAA and

analytical results are compared with those of other analytical methods. To identify the

accuracy and precison of analytical procedure, analyses of the standard reference materials

(NIST SRM 398) were carried out. The homogeneity of samples were assessed by means of

the elements such as Ag, As, Co, Sb, Se and Zn. The uncertainties and the concentration of

consitituent elements were determined and also showed the possibility of use for analytical

quality control.

IV. Future Plans for Research and Development

We will car-ry out the analysis of airborne particulate matter as well as other

environmental and biological samples for air and marine environmental pollution studies.

This workscope is also involved as a part of our long term project related to a intensive

study on application of NAA. Particularly, we are interested in analytical quality assurance

of NAA. In addition, to improve the analytical accuracy and detection limit, to increase the

number of available elements, we are making plans for the development of various

irradiation facilities and eipment and the research of analytical techniques using chmical

analysis. However, to make the above project a success application of international standards

are essential, i.e., standardization and harmonization of analytical techniques in sampling and

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sample preparation, analytical procedures and data evaluation, including K. method as well

as chemornetrics. Collaboration with RCA member states, IAEA and other nations will be

promoted.

V. References

[11 Y. S. Chung, Y. J. Chung, E. S. Jeong and S. Y. Cho, 'Determination of Trace Elements

in Arborne Particulates by INAA' J Kor. Ncl. Soc, 27 2 1995) 234.

[21 Y. S. Chung, Y. J. Chung, E. S. Jung and S. Y. Cho ;'Comparison and Determination of

Environmental Standard Samples by Instrumental Neutron Activation Analysis', J.

Radioanal. Ncl. Chem., 217, 1 1997) 71-76.

[31 Y. S. Chung, Y. J. Chung, E. S. Jeong and S. Y. Cho 'Study on Air Pollution

Monitoring in Korea using Instrumental Neutron Activation Analysis', J Radioanal.

Nucl. Chern, 217, 1 1997) 83-89.

[41 Y. S. Chung, J. H. Moon, Y. J. Chung, S. Y. Cho and S. H. Kang, 'Study on Ambient

Environmental Monitoring using Instrumental Neutron Activation Analysis of Arborne

Particulate Matter', Proceedings of the Korean Nuclear Society Autumn Meeting, Vol.

2, 451-457, Taegu, Korea, October 1997.

[51 Yong Sam Chung, Annual Report of Korea Atomic Energy Research Institute,

KAERI/RR-1745/96

[61 Yong Sam Chung, Technical Report of Korea Aton-dc Energy Research Institute,

KAERL/TR-898/971.

[71 Y. S. Chung, Y. J. Chung, and J. H. Moon ; 'Intercomparison and Determination of

Trace Elements in Sediment by Instrumental Neutron Activation Analysis', Proceedings

of the 5th Asian Symposium on Research Reactor, vol. 1, p471, 29-31 May 1996,

Taejon, Korea.

[81 J. H. Lee, K. H. Cho, J. C. Woo, M. S. Han and Y. S. Chung ; Determination of Trace

Elements in High Purity Copper by INAA, GFAAS and CP-AES', Proceedings of

Forth International Conference on Methods and Applications of Radioanalytical

Chemistry, 611 April 1997, Kailua-Kona, Hawaii Proceedings of J. Radioarral. Nucl.

Chern, 1998.

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Table 1. Characteristics and Available Maximum Neutron Flux(30MW) with

Irradiation Sites of Pneumatic Transfer System for Neutron Activation Analysis.

N60006+loxlrfadigi6h

PJMion SpecificationY NA Jhoenal

C4.82 MOV) 0A625 W- Manual System: AutoAland Control, Loader

System 1 - For Production and 2 Receivers, Air Cushion(NAA 1) 2.4 x 1 0"' 3.9 x 0'3 of RI and NAA PE Capsule: 42cc, D28mm, L80mm

Air Pressure: 1.0 barSimple shutter: Shielded loader and ReceiverAutomatic System: Auto PC Emergency

System 2 - For NAA only Control, Air Cushion, 100 Sample Loader,(NAA 2 2.5 x 1 0" 9.4 x 1013 (ENAA, DNAA) 11 Diverters and Delay Stacker

PE Capsule 27cc, D25mm, L62mm

(NAA 3 1.3 x 1012 1.6 x 10" Air Pessure 0.6 barPreset Ti, Td, TcTwo Count End

Tab le 2 Gamma-Ray Counting System of NAA Laboratory.

• HP Ge Semiconductor Detector, EG&G ORTEC.GMX Series 3 keV-10 MeV) and GEM Series (50 keV-10 MeV) 25 RelativeEfficiency, 19 keV Resolution at 1332 KeV of 6OCo, Peak to Compton Ratio 45:1

• FIP Ge Semiconductor Detector, Oxford/TENNELEC.CP Series 40 keV-10 MeV) 25 Relative Efficiency, 1.85 keV Resolution at 1332

KeV of Co, Peak to Compton Ratio 57:1• LEPS Si(Li) Detector, G&G ORTEC.; SLP Series keV-60 keV)• Low Background P Shield for Ge Detector, EG&G ORTEC.

47r-10 cm thick Low Background Virgin Lead, Graded Cu & Cd Liner 28 x 41 cmCavity Pb Shielding Box 35 x 40 cm, 40 x 45 cm Cavity, Cu & Cd Lined)

• Multichannel Analyser, EG&G ORTEC.918A MCB; 8K Channel ADC(10,us), 8K C Data Memory, Counting Loss Correction919A MCB; 16K Channel ADCUus), 64K C Data Memory, Digital Stabilizer, MASTRO-11Emulation Software(ADCAM 100)

• Multichannel Analyser, OxfordAssayer S/W and 0xfordWN-MCA S/W including Auto Sample Changer Program.

• Application Software Program for NAA Gamma-Ray Spectrum Analysis SoftwareKNAA/UNICAL(KAERI), GANAAS(IAEA), GLIGAM/OMNIGAM(EG&G ORTEC)

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Table 3 Measured Thermal, Epithermal and Fast Neutron Flux of NAA Irradiation

Holes and Cadimium Ratios at 22MW Thermal Power.

Irradiation Neutron flpx� 6&m sec. cadirnium

Hole Thermal, Ot EpithermaL.C Fast Of RAWAW�

NAA 1 1.75±0.02 x 10'3 3.62+2.13 x 101U 3.25±0.14 x 10"' 250

NAA 2 5.78+0.56 X loll 3.40±0.41 x 10"' 3.85±0.31 x 109 35(Cd lined)

NAA 3 7.60+0.06 x 10" 4.35±1.85 x 10" 6.80+0.70 x 10" 13

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Table 4 Analytical Results of Trace Elements in Polyethylene Rabbit and

Various Polyethylene Samples by INAA and ICP. Concentration in ppb.

Element Rabbit HN1 HN2 TR1 TR2 TR3 LG1 LG2

Ca(ppm) - 150 160 270 <3.7 <23 230 300Mg(ppm) 140 110 110 3.6 150 0.28 23 26AI(ppm) 74 76 52 8.7 57 0.20 13 23CI(ppm) 38 100 79 19 53 0.19 140 140Ti(ppm) 6.1 4.1 5.2 1.4 4.1 0.17 9.4 13CU - <280 <240 <130 680 54 <170 <240v 20 <4 <3 <2 440 1.5 <2 <2Mn 170 <6 <6 6.78 <19 4.4 8.8 10Na(ppm) 1.3 0.26 0.43 <0.02 0.20 1.0 0.65 0.92Fe(ppm) 2.3 1.5 <0.75 <0.84 <0.46 <0.55 0.52 0.81MO 280 - - - <1100 <1600 <260 <260As 0.51 <0.71 0.66 <.1.3 1.2 <1.2 <0.35 <0.43Br 90 <2.4 3.0 5.0 4.6 5.4 8.00 51Sb 3.1 <1.1 2.9 2.3 <1.8 <2.4 4.4 55La 10 <0.16 <0.14 <0.18 1.1 9.9 1.3 0.72Au 0.44 0.028 <0.015 <0.01 0.059 0.067 <0.009 <0.019Cd 30 <24 <28 <12 <32 <51 <6.7 <15Cr 310 21 20 37 <7.5 18000 5.2 12Ga 2.9 <38 <42 <26 <25 <6.2 < 13 < 1.5Hf 0.66 <0.72 <0.69 <0.71 <0.64 2.5 <0.4 <0.75Hg 1.7 <2.9 <2.8 <2.1 <2.2 <3.0 <1.1 < 16Co 4.3 9.2 8.6 3.8 5.5 6.3 2.8 3.4Zn 60 <74 110 <70 160 74 <30 55Cs 1.3 <3.1 7.1 <2.5 <1.2 <1.4 <0.71 <2.6Eu - <2.0 1.7 1.1 <1.1 <1.3 <0.86 <0.34Ba 0.18 0.11 840 <860 <270 <310 <190 <210SC - <0.06 0.23 0.20 <0.044 <0.061 0.076 0.057K 250 <2600 <5500 <1060 <3300 <530 <820 <240Zr - <660 800 <760 <210 <260 <280 <300Ce 50 9.5 <5.9 17 <4.5 <9.5 <2.8 <2.8SM 0.07 0.23 <0.1 <0.13 0.10 0.27 0.13 0.060Rb - <24 <47 57 <21 100 <17 <20Th 1.4 <1.2 <1.1 <0.84 <0.59 <0.90 <0.31 <0.48w 1.1 <4.3 <4.0 <3.4 <2.9 <5.0 <0.85 < 14

239 -

ST

CN

NDI

ST 2

J,,Ir4

CANAL 8

ND2;8

ED

,�D3"

ST 4

Figure 1. Location of irrrachation, thimbles.

240 -

.)J

Figure 2. The photograph of PTS laboratory.

- 241-

MMUMNSMEMEW

Hand Loader Caps in Stack psi

-1�7-1 No PD-12 (# 113.1.yTirne PS2

HI-RAD

IRadiation Hig IV 4

PD-13 -3

PO-11

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DIV 2Dek

!,k, PD-10Stac

Caps NoAuto

DIV-6 Loader cap. No DIV-1

DIV

PD-6 FC -.P-.PD-5

PD-4 Cnt PD-3 PDA Pool PD-2End End Caps No

Caps No Caps No Caps No Cap No

77 GM Tub,

U CELLI LJ PD-7

ICrATime I jhtdTime lHoldTime, Drop Out

ToW elayTime j;,ii1jijv;1� R 1111 11;,j gippIl!r fl, N lup I !11" 1, �11" , ;� 1n'q1z j1!!1i

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re!� PD12 HI-RAD

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PD-13 1. .!DFV-3 ISO

PD-11

D PD-9 J; 1 F 9 I %W K., J.2

Detay1? I" 41',� , 4 5 i I "0... ... "W". SlackerIV 1

DD IV- Auto SOU

Loader SOL131

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Counter Drop OutEnd "Rh Poo4End

E Ww"Jow \16th Line, PoolEnd GM Tube�z�:SUIL

T�-i smpg Fir PD-7 L/RIC ce, -- 'o; 111w."', J C111", Delay TimeL

�Caps �N- Count Time Irradiation Time bropped C!�

'evil :00:00ON, F�Re c:%Iew\ptsoA

Figure 3 The process flow diagram of automatic pneumatic transfer system.

242 -

1.80

1.75 Detector: Au std. solutionT1/2 2.7d(64.8 hr)

1.70 y 411.8 keVcr 98.8 b

1.65 f= 100%a.w = 196.77

1.60�2C) 1.55

1.50 - - - - - - - - - - - - - - - - - - -- - - - - - - - - - - - - - - - - - -

X 1.45 3;J Mean value: 1.5014 0.0247) x 101

4-i 1.40

1.35

1.30

1.25

1.200 60 120 180 240 300 360 420 480 540 600 660

Time (min)

Figure 4 Typical Fluctuation Test of the Thermal Neutron Flux

on PTS Irradiation Hole in 17MW.